Message path selection within a network

ABSTRACT

Embodiments relate to path selection for packet transfer in a network. An aspect includes a method of selecting a path among a plurality of paths in a network for transfer of a packet from a first system to a second system in the network. The method includes storing, in a memory device, a static path performance vector indicating a tier among a plurality of tiers corresponding with each of the plurality of paths, each of the plurality of tiers corresponding with a relative performance level. The method also includes maintaining a path availability bit vector indicating an availability of each of the plurality of paths, and selecting, using a processor, the path among the plurality of paths based on the path performance vector and the path availability bit vector.

BACKGROUND

The present invention relates generally to packet delivery, and morespecifically, to message path selection within a network.

A number of systems may be part of a network. Each of these systems maysend and receive packets from other systems within the network over oneof a number of possible links or paths. While the multiple links orpaths are installed within the network for redundancy, these links arenot all the same.

SUMMARY

Embodiments include a method, system, and computer program product forpath selection. The computer program product for implementing a pathselection includes a computer readable storage medium having programinstructions embodied therewith that are readable by a processor tocause the processor to perform a method. The method includes storing astatic path performance vector indicating a tier among a plurality oftiers corresponding with each of the plurality of paths, each of theplurality of tiers corresponding with a relative performance level. Themethod also includes maintaining a path availability bit vectorindicating an availability of each of the plurality of paths, andselecting, by the processor, the path among the plurality of paths basedon the path performance vector and the path availability bit vector.

The method of selecting a path among a plurality of paths in a networkfor transfer of a packet from a first system to a second system in thenetwork includes storing, in a memory device, a static path performancevector indicating a tier among a plurality of tiers corresponding witheach of the plurality of paths, each of the plurality of tierscorresponding with a relative performance level. The method alsoincludes maintaining a path availability bit vector indicating anavailability of each of the plurality of paths, and selecting, using aprocessor, the path among the plurality of paths based on the pathperformance vector and the path availability bit vector.

A system to select a path among a plurality of paths in a network fortransfer of a packet from a first system to a second system in thenetwork includes a memory device storing a static path performancevector configured to indicate a tier among a plurality of tierscorresponding with each of the plurality of paths, each of the tierscorresponding with a relative performance level. The system alsoincludes a processor configured to maintain a path availability bitvector indicating an availability of each of the plurality of paths andselect the path among the plurality of paths based on the pathperformance vector and the path availability bit vector.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The subject matter which is regarded as embodiments is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The forgoing and other features, and advantages ofthe embodiments are apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings in which:

FIG. 1 is a block diagram of a path selection system within a networkaccording to embodiments;

FIG. 2 illustrates an exemplary path performance vector according to anembodiment;

FIG. 3 illustrates an exemplary path availability bit vector accordingto an embodiment; and

FIG. 4 shows the process flow of a method of selecting a path totransfer a packet within a network according to embodiments describedherein; and

FIG. 5 is a flow diagram of the path selection process according to anembodiment.

DETAILED DESCRIPTION

Embodiments described herein relate to selecting a link or path fordelivery of a data packet or message from one system within a network toanother.

Some previous path selection schemes consider the amount of interleavedusage on the candidate paths and select a path with the least amount ofsuch usage. This scheme assumes that the native performancecharacteristics of the candidate paths are the same. Other strategiesinvolve the use of deterministic path selection algorithms that optimizeresponse time. These algorithms require knowledge about a number offactors related to the link itself (e.g., link length, data rate, ratedbandwidth, number of simultaneous operations supported) and the presentstate of the link (e.g., number of operations in flight, amount of datain those operations). The algorithms require relatively large time andcomputing resources, as well. The embodiments described herein relate tocategorizing the paths into performance tiers and using a combination ofthis static tier information and path availability information to selecta path.

FIG. 1 is a block diagram of a path selector 110 within a network 100according to embodiments. Systems 120A and 120B are shown as exchanginga data packet in FIG. 1, but the network 100 may include any number ofother systems 120. In the exemplary network 100 shown in FIG. 1, system120A sends a data packet to system 120B over path 130 a, but other paths(130 b and 130 c in the example) are available, as well. Each of thesystems 120 in the network 100 has access to the path selector 110.Every system 120 accesses the path selector 110 to determine a path 130prior to sending a packet. The path selector 110 includes an inputinterface 112, one or more processors 114, one or more memory devices116, and an output interface 118. In alternate embodiments, some or allof the components of the path selector 110 may be included in each ofthe systems 120. The memory device 116 or another memory deviceaccessible to the path selector 110 stores a static path performancevector 210 (FIG. 2) indicating a performance tier 220 (FIG. 2) to whicheach path 130 is sorted. Each path 130 has intrinsic characteristics(e.g., transmission speed, bandwidth capabilities, number of physicallines) that facilitate the sorting of each path 130 into a performancetier 220, discussed further with reference to FIG. 2. Each path 130includes one or more lines or communication resources 320 (FIG. 3). Inaddition to the path performance vector 210, the path selector 110 ormemory device accessible by the path selector 110 maintains a pathavailability bit vector 310 (FIG. 3). The path availability bit vector310 indicates availability of each path 130 based on the availability ofeach communication resource 320 within a path 130, as further discussedwith reference to FIG. 3. The path performance vector 210 is static fora given set of paths 130. That is, the path performance vector 210 doesnot change unless a path is modified within, added to, or removed fromthe network 100. On the other hand, the path availability bit vector 310may be updated every time the availability status of a communicationresource 320 of a path 130 changes. In alternate embodiments, the pathavailability bit vector 310 may be updated periodically. By using thepath performance vector 210 and the path availability bit vector 310, asfurther detailed below, the highest performance path 130 available foruse by a system 120 is selected.

FIG. 2 illustrates an exemplary path performance vector 210 according toan embodiment. In the example shown in FIG. 2, eight paths 130 sortedinto four tiers are available to carry packets between systems 120within the network 100. As shown in the exemplary path performancevector 210, the tier 220 in which a path 130 is sorted may be indicatedwith a one, while other tiers 220 are indicated with a zero. Forexample, path 1, path 3, and path 4 are indicated as being in Tier 1,while path 2 is indicated as being in Tier 2. The ordering of the tiers220 may correspond with performance. For example, Tier 1 220 may includepaths 130 with the fastest transmission speeds while Tier 4 220 includespaths 130 with the slowest transmission speeds, as indicated in FIG. 2.Each row (tier 220) shown in FIG. 2 may correspond with a byte, witheach bit within each byte indicating whether or not a particular path130 is in the corresponding tier 220. As should be clear, no two bytescould have the same bits set (i.e., no path 130 could be in more thanone tier 220). For example, byte index 0 may correspond with tier 220Tier 1 (first row) and byte index 3 may correspond with tier 220 Tier 4(row 4).

When available, a path 130 in the highest performance tier 220 isselected. For the example shown in FIG. 2, if any of the paths 130 path1, path 3, or path 4 is available, the path 130 would be selected. Whenmore than one path 130 is available in the highest performance tier 220(e.g., all of the paths 130 path 1, path 3, and path 4 are available),then the paths 130 path 1, path 3, and path 4 may be selected in turn orin a round-robin fashion based on subsequent path requests from systems120. The number of tiers 220 may be selected based on a range ofcharacteristics exhibited by the paths 130. Alternately, a number oftiers 220 may be predefined and the characteristics of the paths 130 maybe sorted according to the number of available tiers 220. As notedabove, the path performance vector 210 is static until a change(modification, addition, removal) of a path 130 occurs in the network100.

FIG. 3 illustrates an exemplary path availability bit vector 310according to an embodiment. The derivation of the path availability bitvector 310 from a communication resource availability vector 330 isdescribed. Eight paths 130, each having four communication resources 320are shown in the example. As shown, the path availability bitcorresponding to a communication resource 320 that is available may beone while the path availability bit corresponding to a communicationresource 320 that is not available may be zero. For example,communication resources 320 cr 1, cr 3, and cr 4 for path 130 path 1 areindicated as being available while communication resource 320 cr 2 ofpath 130 path 1 is indicated as unavailable. When a path 130 has noavailable communication resources 320 (e.g., path 130 path 4 in FIG. 3),that path 130 is unavailable and cannot be selected to deliver a packet.This information is reflected in the path availability bit vector 310.In the example, only path 130 path 4 is unavailable. Thus, only the bitin the path availability bit vector 310 corresponding to path 130 path 4is zero.

FIG. 4 shows the process flow of a method of selecting a path 130 totransfer a packet within a network 100 according to embodimentsdescribed herein. At block 410, establishing performance tiers 220includes ordering of the performance tiers 220. That is, the tiers 220are ranked by performance level (e.g., by tiers 220 representing thefastest channels to tiers 220 representing the slowest channels). Atblock 420, sorting each path 130 into a corresponding tier 220 may bebased on link speed or another characteristic of the paths 130. At block430, the sorting of each path 130 into a tier 220 is used to establish apath performance vector 210 (see e.g., FIG. 2) that is static for agiven set of paths 130. At block 440, maintaining a path availabilitybit vector 310 (see e.g., FIG. 3) involves updating the bitcorresponding to each path 130 based on availability of communicationresources 320 of the path 130 as discussed with reference to FIG. 3.Based on the static path performance vector 210 and the pathavailability bit vector 310, selecting a path 130, at block 450, isexecuted as detailed below with reference to FIG. 5.

FIG. 5 is a flow diagram of the path 130 selection process according toan embodiment. Beginning with the byte corresponding to the highestperformance tier 220 (e.g., first row corresponding to tier 220 Tier 1in FIG. 2), a bitwise AND operation is performed at 510 of the pathperformance vector 210 byte and the path availability bit vector 310(see e.g., FIG. 3). With the first row of the exemplary path performancevector 210 shown in FIG. 2 and the path availability bit vector 310shown in FIG. 3, the following AND operation would be performed:[10110000] AND [11101111]=[10100000]]  [EQ. 1]According to the process flow shown in FIG. 5, the result of the bitwiseAND is checked at 520. The result of EQ. 1 indicates that path 1 andpath 3 are in the highest performance tier 220 and are available forselection. This result, when checked at 520, would lead to theimplementation of a round-robin scheme (530) to use path 1 and path 3 inturn. In this case, path 1 may be selected at 540. If the result (at510) had included only one “1,” then the corresponding path would beselected at 540. If the result (of 510 checked at 520) had been allzeroes, indicating that no paths 130 were available in the highestperformance tier 220, then, at 550, it would first be checked whetherthe current tier 220 were the lowest performance tier 220 (i.e., all thetiers 220 have been checked). If the outcome of the check at 550 is thatthe current tier 220 is the lowest performance tier 220, then theprocess comes to an end because no paths 130 were available in any ofthe tiers. If the outcome of the check at 550 is that the current tier220 is not the lowest performance tier 220, then the next highestperformance tier 220 is selected at 560 (i.e., the next row in the pathperformance vector 210 shown in FIG. 2 is selected) and the bitwise ANDis performed again at 510, iteratively as shown.

Technical effects and benefits include selection of the highestperformance path available to transport a packet based on updatingavailability information.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, element components,and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A computer program product for implementing apath selection, the computer program product comprising: anon-transitory computer readable storage medium having programinstructions embodied therewith, the program instructions readable by aprocessor to cause the processor to perform a method comprising: storinga static path performance vector indicating a plurality of tiers, eachtier containing a plurality of paths, wherein each of the plurality oftiers correspond to a performance level within a range of values;ranking each of the plurality of tiers based upon the performance level;maintaining a path availability bit vector indicating an availability ofeach of the plurality of paths; selecting, by the processor, a pathamong the plurality of paths based on the path falling within a highestranked tier and based on the availability of the path, wherein theselecting the path includes performing an AND operation on the pathavailability bit vector and a byte of the path performance vectorcorresponding with a tier among the plurality of tiers, the ANDoperation indicating paths among the plurality of paths that are bothavailable and sorted into the tier among the plurality of tiers, andwherein the performing the AND operation is done iteratively beginningwith the byte of the path performance vector corresponding to a highestperformance tier among the plurality of tiers and continuing with thebyte of the path performance vector corresponding to a next highestperformance tier until an available path among the plurality of paths isindicated.
 2. The computer program product according to claim 1, furthercomprising establishing the path performance vector based on sortingeach of the plurality of paths into the respective tier among theplurality of tiers based on a link speed of each of the plurality ofpaths.
 3. The computer program product according to claim 1, wherein themaintaining the path availability bit vector includes setting acorresponding bit to indicate unavailability when every communicationresource of a path among the plurality of paths is in use.
 4. Thecomputer program product according to claim 1, wherein when theperforming the AND operation indicates two or more paths among theplurality of paths that are both available and sorted into the tieramong the plurality of tiers, each of the two or more paths is selectedin turn in a round-robin fashion.
 5. The computer program productaccording to claim 1, further comprising updating the path performancevector when a path among the plurality of paths is added, removed, ormodified.
 6. A method of selecting a path among a plurality of paths ina network for transfer of a packet from a first system to a secondsystem in the network, the method comprising: storing, in a memorydevice, a static path performance vector indicating a plurality oftiers, each tier containing a plurality of paths, wherein each of theplurality of tiers correspond to a performance level within a range ofvalues; ranking each of the plurality of tiers based upon theperformance level; maintaining a path availability bit vector indicatingan availability of each of the plurality of paths; selecting, using aprocessor, the path among the plurality of paths based on the pathfalling within a highest ranked tier and based on the availability ofthe path, wherein the selecting the path includes performing an ANDoperation on the path availability bit vector and a byte of the pathperformance vector corresponding with a tier among the plurality oftiers, the AND operation indicating paths among the plurality of pathsthat are both available and sorted into the tier among the plurality oftiers, and wherein the performing the AND operation is done iterativelybeginning with the byte of the path performance vector corresponding toa highest performance tier among the plurality of tiers and continuingwith the byte of the path performance vector corresponding to a nexthighest performance tier until an available path among the plurality ofpaths is indicated.
 7. The method according to claim 6, furthercomprising establishing the path performance vector based on sortingeach of the plurality of paths into the respective tier among theplurality of tiers based on a link speed of each of the plurality ofpaths.
 8. The method according to claim 6, wherein the maintaining thepath availability bit vector includes setting a corresponding bit toindicate unavailability when every communication resource of a pathamong the plurality of paths is in use.
 9. The method according to claim6, wherein when the performing the AND operation indicates two or morepaths among the plurality of paths that are both available and sortedinto the tier among the plurality of tiers, each of the two or morepaths is selected in turn in a round-robin fashion.
 10. A system toselect a path among a plurality of paths in a network for transfer of apacket from a first system to a second system in the network, the systemcomprising: a memory device storing a static path performance vectorconfigured to indicate a plurality of tiers, each tier containing aplurality of paths comprising, wherein each of the tiers correspond witha performance level within a range of values; a processor configured torank each of the plurality of tiers based upon the performance level; aprocessor configured to maintain a path availability bit vectorindicating an availability of each of the plurality of paths and selecta path among the plurality of paths based on the path falling within ahighest ranked tier and based on the availability of the path, whereinthe selecting the path includes performing an AND operation on the pathavailability bit vector and a byte of the path performance vectorcorresponding with a tier among the plurality of tiers, the ANDoperation indicating paths among the plurality of paths that are bothavailable and sorted into the tier among the plurality of tiers, andwherein the performing the AND operation is done iteratively beginningwith the byte of the path performance vector corresponding to a highestperformance tier among the plurality of tiers and continuing with thebyte of the path performance vector corresponding to a next highestperformance tier until an available path among the plurality of paths isindicated.
 11. The system according to claim 10, wherein the processoris further configured to establish the path performance vector based onsorting each of the plurality of paths into the respective tier amongthe plurality of tiers based on a link speed of each of the plurality ofpaths.
 12. The system according to claim 10, wherein the processormaintains the path availability bit vector by setting a correspondingbit to indicate unavailability when every communication resource of apath among the plurality of paths is in use.
 13. The system according toclaim 10, wherein when the AND operation indicates two or more pathsamong the plurality of paths that are both available and sorted into thetier among the plurality of tiers, the processor is configured to selecteach of the two or more paths in turn in a round-robin fashion.